1. Field of the Invention
The present invention relates generally to a bicycle, and in particular to a gear-shifting handgrip of the bicycle.
2. Prior Arts
A conventional bicycle gear-shifting handgrip is shown in FIGS. 1, 2A, and 2B, generally designated with reference numeral 1, which allows for hand gripping by a bicycle rider for selectively doing gear shifting. The handgrip 1 comprises a main body 11 mounted on a tube that is fixedly fit over an end of a bicycle handlebar (not shown) and a tubular grip member 12 rotatably fit over the tube of the main body 11 whereby relative rotation is allowed between the main body 11 and the grip member 12. A crank 111 is rotatably fixed on the main body 11 and a transmission cable 121 is connected between the crank 111 and the grip member 12. When the rider rotates the grip member 12, the crank 111 is also rotated. A gear-shifting cable 112 extends from the crank 111 whereby when the crank 111 is rotated, the cable 112 is withdrawn to induce gear shifting.
The grip member 12 has a cylindrical projection having a side wall 125 in which a resilient member 123 is embedded. The side wall also defines a hole 122 to receive and retain an end of the transmission cable 121. A ratcheting ring 113 is fit over the side wall 125 of the grip member 12. The ratcheting ring 113 has an inner circumferential surface along which a plurality of axially-extending recesses 1131 is distributed in an equally spaced manner. A detent pin 124 is arranged between the side wall 125 and the ring 113 and is biased by the resilient member 123 to selectively engage one of the recesses 1131 thereby securing the relative angular position of the grip member 12 with respect to the handle bar, which in turn determines the length of the gear-shifting cable 112 withdrawn due to the rotation of the crank 111.
By forcibly rotating the grip member 12 about the tube of the main body 11, the detent pin 124 is forced to disengage from the current recess 1131 and act against the resilient member 123 to move to a next one of the recesses 1131. This completes the operation of gear-shifting to next sprocket of bicycle derailleur. Each time when the detent pin 124 gains engagement with the next recess 1131 of the ratcheting ring 113, an impact force is generated between the detent pin 124 and the recess 1131 and is transmitted through the grip member 12. This allows the rider to perceive the completion of the gear-shifting operation by tactility of the hand holding the grip member 12.
However, the conventional gear-shifting handgrip is a force-unbalanced device, for there is one detent pin that is movable in radial directions to engage with and/or disengage from the recesses of the ratcheting ring. In addition, such an arrangement makes it a dexterous device (or a sinistral device) only. Interchange between a dexterous rider and a sinistral rider is not possible. The parts are generally not common to both the dexterous device and the sinistral device.